Playbook Conditionals in Ansible

1. Introduction

In Ansible, playbooks are used to define a series of tasks to be executed on managed nodes. Conditionals allow you to control whether a task should be executed based on certain criteria.

2. Conditional Statements

Conditional statements in Ansible are primarily used to determine whether a task should run. The most common way to implement conditionals in Ansible is through the `when` clause.

3. Using the `when` Clause

The `when` clause is used to specify a condition that must be met for a task to execute. This condition can be based on facts, variables, or results of previous tasks.

- name: Install package only if it is not already installed
  apt:
    name: nginx
    state: present
  when: ansible_distribution == 'Ubuntu'
            

4. Example Playbook

Below is an example of a simple playbook that demonstrates conditionals.

---
- hosts: all
  tasks:
    - name: Ensure nginx is installed
      apt:
        name: nginx
        state: present
      when: ansible_os_family == 'Debian'

    - name: Start nginx service
      service:
        name: nginx
        state: started
      when: ansible_service_mgr == 'systemd'
            

5. Best Practices

• Use descriptive variable names to enhance readability.
• Keep conditions simple and straightforward.
• Test conditions to ensure they are correctly applied.
• Combine multiple conditions using logical operators (`and`, `or`).

6. FAQ